As known issues are discovered in Puppet 5.1 and its patch releases, they’ll be added here. Once a known issue is resolved, it is listed as a resolved issue in the release notes for that release, and removed from this list.

PUP-8009: Puppet 5.1.0 introduced support for internationalized strings in Puppet modules. However, this feature can cause significant performance regressions if environment caching is disabled, for instance by setting environment_timeout==0, even if the module doesn’t include internationalized content. Puppet 5.3.2 introduces an optional disable_i18n setting in puppet.conf to avoid using localized strings and restore degraded performance.